This invention relates to a redox battery.
Since electric power can be readily converted into various forms of energy, easily controlled and safely consumed without entailing any environmental pollution, the proportion of the consumption of electric power to the total consumption of all forms of energy combined is increasing year after year. The supply of electric power has a unique characteristic in that the production of electric power and the consumption thereof take place substantially at the same time. The efforts devoted, despite this characteristic restriction, to ensuring reliable supply of electric power of high quality at a fixed frequency under a fixed voltage while promptly responding to incessantly changing power consumption, constitute one important task for those engaged in generation and supply of electric power. In the existing circumstances, nuclear power plants and powerful modern thermal power plants, which do not permit easy change of output but which exhibit highly efficient performance, are operated at their rated maximum capacities while, on the other hand, the hydro-electric power plants, which are capable of quickly responding to frequent fluctuations in power consumption, are operated with their outputs controlled to meet abrupt rises in power consumption during the daytime. The excess electric power which is generated during the nighttime by the nuclear power plants and powerful modern thermal power plants, both economical sources of power, is stored by being utilized to operate pumped-up storage power plants.
With the increasingly harsh topographical conditions of prospective sites for construction of pumped-up storage power plants, the possibility of a power storage system by use of secondary batteries has now become a subject of public discussion. Among secondary batteries existing today, the redox battery which has been developed as a power storage system capable of dispersed installation is worthy of special attention.
The redox batteries developed to date are divided into two types, the redox-flow type secondary batteries which involve storing an aqueous redox solution in a tank and charging or discharging the solution in a flow type electrolytic cell and the redox type fuel batteries. Both types have a common technical task in the sense that the redox system, i.e. an aqueous solution containing an ion with variable valencies as an energy source, is utilized in the form of a positive electrolyte or negative electrolyte. This task resides in the search for a stable redox ion which promises appropriate electromotive force, high solubility and low cost.